This is buried in comments at the Karlheinz Stockhausen Memorial blog administered by the Stockhausen Foundation. It seems as though almost all of Klang was completed before his death:
Dear friends,
the night before Stockhausen died, he finished composing the commission for Orchestra which will be premiered in Bologna next September (ZODIAC for orchestra)
Also to tell you that up to the 21st Hour of KLANG (which is called PARADIES for flute and electronic music), Stockhausen had already composed these works. So although he is now with us only in spirit, there are many more surprises to come!
In June, ASKO will premìere
2006/ KLANG – 10th Hour [ca. 40’]
2007 GLANZ (BRILLIANCE) for bassoon, viola, clarinet, trumpet, trombone, oboe, tubaIn August Ensemble Recherche plans to première
2006/ KLANG – 7th Hour [ca. 30’]
2007 BALANCE for bass clarinet, English horn, fluteAnd Musikfabrik plans to première also in August
2006/ KLANG – 9th Hour [ca. 35’]
2007 HOFFNUNG (HOPE) for violoncello, viola, violinOur copyist will start soon on these scores.
The 6th Hour of KLANG,
SCHÖNHEIT, BEAUTY for flute, trumpet and bass clarinet will be also ready as this will be premièred in October in Lisbon by Suzanne, Marco and me (ca. 30 min.).It is also possible to acquire the rights for a première, as Stockhausen has already finished composing the following hours:
2007 KLANG – 14th Hour [24’10”]
HAVONA for bass and electronic music
(layers 24 – 23 – 22 from COSMIC PULSES)2007 KLANG – 15th Hour [24’]
ORVONTON for baritone and electronic music
(layers 21 – 20 – 19 from COSMIC PULSES)2007 KLANG – 16th Hour [22’40”]
UVERSA for basset-horn and electronic music
(layers 18 – 17 – 16 from COSMIC PULSES)2007 KLANG – 17th Hour [21’40”]
NEBADON for horn and electronic music
(layers 15 – 14 – 13 from COSMIC PULSES)2007 KLANG – 18th Hour [20’40”]
JERUSEM for tenor and electronic music
(layers 12 – 11 – 10 from COSMIC PULSES)2007 KLANG – 19th Hour [19’40”]
URANTIA for soprano and electronic music
(layers 9 – 8 – 7 from COSMIC PULSES)2007 KLANG – 20th Hour [18’40”]
EDENTIA for soprano saxophone and electronic music
(layers 6 – 5 – 4 from COSMIC PULSES)2007 KLANG – 21st Hour [18’]
PARADIES / PARADISE for flute and electronic music
(layers 3 – 4 – 1 from COSMIC PULSES)We thank you for your spiritual support, we need the help of all of you to bring Stockhausens music to the world
Kathinka
Music Matters
Saturday 15 December 2007, 12:15-13:00 (Radio 3)
“Tom Service presents a special programme looking back on the life and music of one of the 20th century’s most distinguished and controversial composers – Karlheinz Stockhausen, who died last week.”
The Rambler 
Most of these pieces are for soloist plus three leyers of the COSMIC PULSES recording. I am very curious as to how complete these scores actually are, or if perhaps there is some process for deriving the solo from the layers chosen. It also raises a question about Stockhausen’s recent practice — did he have a stock of pieces already composed in advance of commissions? That would make considerable sense, as a practical matter, bujt does raise some musicological questions.
I’m greatly interested in hearing about these new pieces, especially the section entitled GLANZ (BRILLIANCE). As a tuba player who is very much fascinated by Stockhausen’s work, I tend to move towards any of his works that include my own instrument.
Daniel – I’m no expert in Stockhausen’s practice, but I believe he worked with a greater or lesser amount of collaboration from Carré onwards, didn’t he? So, there are definitely questions as to how much of this music is pure Stockhausen (but that goes for a lot of his work) – and, indeed, how much of it is written and ready to go at this stage. But it’s good news all the same.
Tim —
I’m no expert either, but my impression is that the amount contributed by Cardew to Carré was far beyond that contributed by his later assistants, and that his manuscripts were quite detailed, ready for his in-house copyist. I believe that he depended more on assistants with the electronic music. I have no idea how the copying has been done since James Ingram stopped working for Stockhausen, but I suspect that there’s an interesting story there.